Question

cos^2 thets -sin^2 theta is equal to:​

Answer 1

$heya \\ \\ \cos {}^{2} ( \alpha ) - \sin {}^{2} ( \alpha ) = \cos(2 \alpha ) \\ \\ or \\ \\ \cos {}^{2} ( \alpha ) - \sin {}^{2} ( \alpha ) = \\ ( \cos( \alpha ) - \sin( \alpha ) ) \times ( \cos( \alpha ) + \sin( \alpha ) ) \\ \\ or \\ \\ \cos {}^{2} ( \alpha ) - \sin {}^{2} ( \alpha ) = 2 \cos {}^{2} ( \alpha ) - 1 \\ \\ or \\ \\ \cos {}^{2} ( \alpha ) - \sin {}^{2} ( \alpha ) = 1 - 2 \sin {}^{2} ( \alpha )$